Stab and ballistic resistant articles and the process of making

ABSTRACT

Dimensionally stable open woven fabrics formed from a plurality of high tenacity warp elongate bodies interwoven and bonded with a plurality of transversely disposed, high tenacity weft elongate bodies, composite articles formed therefrom, and to a continuous process for forming the composite articles.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Divisional of co-pending U.S. application Ser. No.14/996,343, filed Jan. 15, 2016, which is a Divisional of U.S.application Ser. No. 13/835,008, filed Mar. 15, 2013, now U.S. Pat. No.9,243,354 which issued on Jan. 26, 2016, the disclosures of which areincorporated by reference herein.

BACKGROUND Technical Field

This technology relates to stab resistant, closed woven compositearticles formed by thermally fusing an open woven fabric formed fromhigh tenacity, thermoplastic elongate bodies, and to a continuousprocess for forming the composite articles.

Description of the Related Art

High tenacity fibers, such as SPECTRA® polyethylene fibers or aramidfibers such as KEVLAR® and TWARON® fibers, are known to be useful forthe formation of articles having excellent ballistic resistance.Ballistic resistant articles formed from high tenacity tapes are alsoknown. Articles such as bullet resistant vests, helmets, vehicle panelsand structural members of military equipment are typically made fromfabrics comprising high tenacity fibers or tapes because of their veryhigh strength to weight performance. For many applications, the fibersor tapes may be formed into woven or knitted fabrics. For otherapplications, the fibers or tapes may be encapsulated or embedded in apolymeric matrix material and formed into non-woven fabrics. In onecommon non-woven fabric structure, a plurality of unidirectionallyoriented fibers are arranged in a generally coplanar, coextensiverelationship and coated with a binding matrix resin to bind the fiberstogether. Typically, multiple plies of such unidirectionally orientedfibers are merged into a multi-ply composite. See, for example, U.S.Pat. Nos. 4,403,012; 4,457,985; 4,613,535; 4,623,574; 4,650,710;4,737,402; 4,748,064; 5,552,208; 5,587,230; 6,642,159; 6,841,492; and6,846,758, all of which are incorporated herein by reference to theextent consistent herewith.

Composites fabricated from non-woven fabrics are known to stopprojectiles better than woven fabric composites because the componentfibers in non-woven fabrics are not crimped like the fibers in wovenmaterials. Fiber crimping reduces the ability of the fibers to stay intension and immediately absorb the energy of a projectile, compromisingtheir effectiveness. In addition, projectile damage to non-woven fabricsis more localized compared to woven fabrics, allowing for enhancedmulti-hit performance. However, woven composites are more stab resistantthan traditional non-woven fabrics formed from parallel fiber arrays,because the mechanically interlocking woven fabric structure createssuperior friction than that is better at preventing blades from piercingthrough the fabric.

Nevertheless, stab resistant woven fabric articles of the related artremain imperfect. Such woven fabrics require a very tight weave (i.e. apick count of greater than 56×56 per inch) so that the fabric or fabriclayers will not shift on blade impact and to create sufficient frictionto prevent the blade from piercing the fabric. Creating woven fabrics ofsuch high density requires the use of very fine, high quality yarns thatare expensive to manufacture. Also, the use of such fine yarns requiresthat they be highly twisted and/or highly commingled, but the fine yarnsare delicate and often break during twisting or commingling, keepingproductivity low. Finally, composites formed from twisted fibers areless effective at stopping bullets or other projectiles than compositesformed from untwisted fibers. Accordingly, there is an ongoing need inthe art for improved woven ballistic resistant composites having bothsuperior stab resistance and superior ballistic resistance. The presentinvention provides a solution to this need.

SUMMARY

The invention provides a woven fabric comprising a plurality of warpelongate bodies interwoven and bonded with a plurality of transverselydisposed weft elongate bodies, said warp elongate bodies and weftelongate bodies each comprising thermoplastic high tenacity elongatebodies having a tenacity of at least about 14 g/denier and a tensilemodulus of at least about 300 g/denier, wherein immediately adjacentwarp elongate bodies are spaced apart from each other by a distanceequivalent to at least about 10% of the width of the warp elongatebodies and immediately adjacent weft elongate bodies are spaced apartfrom each other by a distance equivalent to at least about 10% of thewidth of the weft elongate bodies.

The invention also provides closed, fused sheets formed from a wovenfabric, and multilayer articles formed from said closed, fused sheets.

The invention further provides a process for forming a dimensionallystable open fabric, the process comprising:

a) providing a woven fabric comprising a plurality of warp elongatebodies interwoven and bonded with a plurality of transversely disposedweft elongate bodies, said warp elongate bodies and weft elongate bodieseach comprising thermoplastic high tenacity elongate bodies having atenacity of at least about 14 g/denier and a tensile modulus of at leastabout 300 g/denier, wherein immediately adjacent warp elongate bodiesare spaced apart from each other by a distance equivalent to at leastabout 10% of the width of the warp elongate bodies and immediatelyadjacent weft elongate bodies are spaced apart from each other by adistance equivalent to at least about 10% of the width of the weftelongate bodies;b) at least partially melting the thermoplastic polymer of the hightenacity warp elongate bodies and/or the high tenacity weft elongatebodies; andc) allowing the melted thermoplastic polymer of the high tenacity warpelongate bodies and/or the high tenacity weft elongate bodies tosolidify, whereby the high tenacity warp elongate bodies and the hightenacity weft elongate bodies are bonded to each other, thereby forminga dimensionally stable open fabric.

The invention still further provides a process for forming a ballisticresistant closed, thermally fused multilayer article comprising:

a) providing at least one open woven fabric comprising a plurality ofwarp elongate bodies interwoven and bonded with a plurality oftransversely disposed weft elongate bodies, said warp elongate bodiesand weft elongate bodies each comprising thermoplastic high tenacityelongate bodies having a tenacity of at least about 14 g/denier and atensile modulus of at least about 300 g/denier, wherein immediatelyadjacent warp elongate bodies are spaced apart from each other by adistance equivalent to at least about 10% of the width of the warpelongate bodies and immediately adjacent weft elongate bodies are spacedapart from each other by a distance equivalent to at least about 10% ofthe width of the weft elongate bodies;b) providing at least one closed, fused sheet formed from a wovenfabric, said woven fabric comprising a plurality of warp elongate bodiesinterwoven and bonded with a plurality of transversely disposed weftelongate bodies, said warp elongate bodies and weft elongate bodies eachcomprising thermoplastic high tenacity elongate bodies having a tenacityof at least about 14 g/denier and a tensile modulus of at least about300 g/denier, wherein immediately adjacent warp elongate bodies arespaced apart from each other by a distance equivalent to at least about10% of the width of the warp elongate bodies and immediately adjacentweft elongate bodies are spaced apart from each other by a distanceequivalent to at least about 10% of the width of the weft elongatebodies, wherein the closed, fused sheet has substantially no gapsbetween immediately adjacent high tenacity elongate bodies and whereinsaid high tenacity elongate bodies do not overlap;c) adjoining the at least one open woven fabric and the at least oneclosed, fused sheet together; andd) thermally pressing the adjoined at least one woven fabric and atleast one fused sheet together under conditions sufficient to attach thewoven fabric to the fused sheet and to flatten the high tenacityelongate bodies in the woven fabric, thereby causing the longitudinaledges of the immediately adjacent high tenacity warp elongate bodies inthe woven fabric to contact each other, whereby there are substantiallyno gaps between said immediately adjacent high tenacity warp elongatebodies and wherein said high tenacity warp elongate bodies do notoverlap.

The invention still further provides a process for forming a closed,thermally fused multilayer article comprising adjoining a woven fabricwith a web comprising a parallel array of high tenacity elongate bodies,wherein the high tenacity elongate bodies of the web are positionedperpendicular to the high tenacity warp elongate bodies of the wovenfabric, and thermally pressing the adjoined woven fabric and web underconditions sufficient to attach the woven fabric to the web and toflatten the high tenacity elongate bodies of both the woven fabric andthe web respectively, thereby causing longitudinal edges of theimmediately adjacent high tenacity elongate bodies in the woven fabricand the web respectively to contact each other, whereby there aresubstantially no gaps between said immediately adjacent high tenacityelongate bodies and wherein said high tenacity elongate bodies do notoverlap.

The invention still further provides a process for forming a closed,thermally fused multilayer article comprising adjoining a closed, fusedsheet with a web comprising a parallel array of high tenacity elongatebodies, wherein the high tenacity elongate bodies of the web arepositioned perpendicular to the high tenacity elongate bodies of thefused sheet, and thermally pressing the adjoined fused sheet and webunder conditions sufficient to attach the fused sheet to the web and toflatten the high tenacity elongate bodies of the web, thereby causinglongitudinal edges of the immediately adjacent high tenacity elongatebodies in the web to contact each other whereby there are substantiallyno gaps between said immediately adjacent high tenacity elongate bodiesand wherein said high tenacity elongate bodies do not overlap.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective-view schematic representation of a woven fabrichaving spaced apart high tenacity elongate bodies in both thelongitudinal warp direction and the lateral weft direction.

FIG. 2 is a perspective-view schematic representation illustrating theformation of a closed, fused sheet by the thermal fusion of a singleopen woven fabric having spaced apart high tenacity elongate bodies inboth the longitudinal warp direction and the lateral weft direction.

FIG. 3 is a perspective-view schematic representation illustrating theformation of a closed multi-layer fabric where a first open woven fabrichaving spaced apart high tenacity elongate bodies in both thelongitudinal warp direction and the lateral weft direction is thermallyfused together with a second woven fabric having spaced apart hightenacity elongate bodies in both the longitudinal warp direction and thelateral weft direction.

FIG. 4 is a perspective-view schematic representation illustrating theformation of a closed, thermally fused multilayer article where an openwoven fabric is thermally fused with a web comprising a unidirectionalarray of longitudinal high tenacity elongate bodies supplied from acreel.

FIG. 5 is a perspective-view schematic representation illustrating theattachment of a first open woven fabric to a second woven fabric bypassage through a first set of rolls before they are fused togetherbetween a second set of rolls.

FIG. 6 is a perspective-view schematic representation illustrating theattachment of an open woven fabric to a unidirectional array oflongitudinal high tenacity elongate bodies supplied from a creel bypassage through a first set of rolls before they are fused togetherbetween a second set of rolls.

FIG. 7 is a perspective-view schematic representation illustrating aconventional plain weave structure having longitudinal warp fibers,lateral weft fibers and selvage loops at its lateral edges.

DETAILED DESCRIPTION

As illustrated in FIGS. 1-6, high strength composite sheets arefabricated by interweaving high tenacity warp elongate bodies withtransversely disposed high tenacity warp elongate bodies. As usedherein, “elongate bodies” are bodies having a length dimension that ismuch greater than the transverse dimensions of width and thickness. Suchincludes monofilaments, untwisted multifilament fibers (i.e. untwistedyarns) that are fused or unfused, untwisted thermally fusedmultifilament tape, or non-fibrous polymeric tape. Such also includestwisted multifilament fibers (i.e. twisted yarns) that are fused orunfused, but it is most preferred that all the elongate bodies formingthe fabrics and fused sheets of the invention are untwisted elongatebodies.

As used herein, a “high tenacity” elongate body is one having a tenacityof at least about 14 g/denier, more preferably about 20 g/denier ormore, still more preferably about 25 g/denier or more, still morepreferably about 30 g/denier or more, still more preferably about 40g/denier or more, still more preferably about 45 g/denier or more, andmost preferably about 50 g/denier or more. Such high tenacity elongatebodies also have a tensile modulus of at least about 300 g/denier, morepreferably about 400 g/denier or more, more preferably about 500g/denier or more, still more preferably about 1,000 g/denier or more andmost preferably about 1,500 g/denier or more. The high tenacity elongatebodies also have an energy-to-break of at least about 15 J/g or more,more preferably about 25 J/g or more, more preferably about 30 J/g ormore and most preferably have an energy-to-break of about 40 J/g ormore. Methods of forming elongate bodies having these combined highstrength properties are conventionally known in the art.

The term “denier” refers to the unit of linear density, equal to themass in grams per 9000 meters of fiber/tape. The term “tenacity” refersto the tensile stress expressed as force (grams) per unit linear density(denier) of an unstressed specimen. The “initial modulus” is theproperty of a material representative of its resistance to deformation.The term “tensile modulus” refers to the ratio of the change intenacity, expressed in grams-force per denier (g/d) to the change instrain, expressed as a fraction of the original fiber/tape length(in/in).

As used herein, the term “tape” refers to a flat, narrow, monolithicstrip of material having a length greater than its width and an averagecross-sectional aspect ratio, i.e. the ratio of the greatest to thesmallest dimension of cross-sections averaged over the length of thetape article, of at least about 3:1. A tape may be a fibrous material ora non-fibrous material. A “fibrous material” comprises one or morefilaments. The cross-section of a polymeric tape of the invention may berectangular, oval, polygonal, irregular, or of any shape satisfying thewidth, thickness and aspect ratio requirements outlined herein.

Such tapes preferably have a substantially rectangular cross-sectionwith a thickness of about 0.5 mm or less, more preferably about 0.25 mmor less, still more preferably about 0.1 mm or less and still morepreferably about 0.05 mm or less. In the most preferred embodiments, thepolymeric tapes have a thickness of up to about 3 mils (76.2 μm), morepreferably from about 0.35 mil (8.89 μm) to about 3 mils (76.2 μm), andmost preferably from about 0.35 mil to about 1.5 mils (38.1 μm).Thickness is measured at the thickest region of the cross-section.

Polymeric tapes useful in the invention have preferred widths of fromabout 2.5 mm to about 50 mm, more preferably from about 5 mm to about25.4 mm, even more preferably from about 5 mm to about 20 mm, and mostpreferably from about 5 mm to about 10 mm. These dimensions may vary butthe polymeric tapes formed herein are most preferably fabricated to havedimensions that achieve an average cross-sectional aspect ratio. i.e.the ratio of the greatest to the smallest dimension of cross-sectionsaveraged over the length of the tape article, of greater than about 3:1,more preferably at least about 5:1, still more preferably at least about10:1, still more preferably at least about 20:1, still more preferablyat least about 50:1, still more preferably at least about 100:1, stillmore preferably at least about 250:1 and most preferred polymeric tapeshave an average cross-sectional aspect ratio of at least about 400:1.

Polymeric tapes are formed by conventionally known methods, such asextrusion, pultrusion, slit film techniques, etc. For example, a unitapeof standard thickness may be cut or slit into tapes having the desiredlengths, which is a desired method for producing tapes from multi-plynon-woven fiber layers. An example of a slitting apparatus is disclosedin U.S. Pat. No. 6,098,510 which teaches an apparatus for slitting asheet material web as it is wound onto said roll. Another example of aslitting apparatus is disclosed in U.S. Pat. No. 6,148,871, whichteaches an apparatus for slitting a sheet of a polymeric film into aplurality of film strips with a plurality of blades. The disclosures ofboth U.S. Pat. Nos. 6,098,510 and 6,148,871 are incorporated herein byreference to the extent consistent herewith. Other exemplary methods aredescribed in U.S. Pat. Nos. 7,300,691; 7,964,266 and 7,964,267, whichare incorporated herein by reference to the extent consistent herewith.It is also known to form narrow tape structures by weaving thin stripsof fabric, which generally may be accomplished by adjusting the settingson any conventional weaving machine, such as those disclosed in U.S.Pat. Nos. 2,035,138; 4,124,420; 5,115,839, which are incorporated byreference herein to the extent consistent herewith, or by use of aribbon loom specialized for weaving narrow woven fabrics or ribbons.Useful ribbon looms are disclosed, for example, in U.S. Pat. Nos.4,541,461; 5,564,477; 7,451,787 and 7,857,012, each of which is assignedto Textilma AG of Stansstad. Switzerland. and each of which isincorporated herein by reference to the extent consistent herewith,although any alternative ribbon loom is equally useful.

Elongate bodies of the invention also include filaments, fibers andyarns. Fibers and yarns are distinguished from filaments in that fibersand yarns are formed from filaments. A fiber may be formed from just onefilament or from multiple filaments. A fiber formed from just onefilament is referred to either as a “single-filament” fiber or a“monofilament” fiber, and a fiber formed from a plurality of filamentsis referred to as a “multi-filament” fiber. A “yarn” is defined as asingle strand consisting of multiple filaments, analogous to amulti-filament fiber. The cross-sections of fibers, filaments and yarnsmay vary and may be regular or irregular, including circular, flat oroblong cross-sections.

The high tenacity elongate bodies may comprise any conventionally knownthermoplastic polymer type having a tenacity of at least about 14g/denier and a tensile modulus of at least about 300 g/denier.Particularly suitable are elongate bodies formed from polyolefins,including polyethylene and polypropylene; polyesters, includingpolyethylene terephthalate, polypropylene terephthalate, andpolybutylene terephthalate; polyamides; polyphenylenesulfide; gel spunpolyvinyl alcohol (PVA); gel spun polytetrafluoroethylene (PTFE); andthe like. Particularly preferred are extended chain polyolefin elongatebodies, such as highly oriented, high molecular weight polyethylene,particularly ultra-high molecular weight polyethylene (UHMW PE) elongatebodies, and ultra-high molecular weight polypropylene elongate bodies.Each of these elongate body types described above is conventionallyknown in the art. Also suitable for producing polymeric elongate bodiesare copolymers, block polymers and blends of the above materials. Forexample, useful elongate bodies may be formed from multi-filamentelements comprising at least two different filament types, such as twodifferent types of UHMW PE filaments or a blend of polyester filamentsand UHMW PE filaments.

Thermoplastic high tenacity elongate bodies are most suitable hereinbecause they are capable of being deformed by thermal, solid statedeformation. Such excludes non-thermoplastic synthetic fibers such ascarbon fibers, aramid fibers, glass fibers, polyacrylic fibers, aromaticpolyamide fibers, aromatic polyester fibers, polyimide fibers, etc.

Specifically most preferred are elongate bodies formed from ultra highmolecular weight polyethylene. Ultra high molecular weight polyethylenefilaments, fibers and yarns are formed from extended chain polyethyleneshaving molecular weights of at least 300,000, preferably at least onemillion and more preferably between two million and five million. Suchextended chain polyethylene fibers/yarns may be grown in solutionspinning processes such as described in U.S. Pat. No. 4,137,394 or4,356,138, which are incorporated herein by reference, or may be spunfrom a solution to form a gel structure, such as described in U.S. Pat.Nos. 4,413,110; 4,536,536; 4,551,296; 4,663,101; 5,006,390; 5,032,338;5,578,374; 5,736,244; 5,741,451; 5,958,582; 5,972,498; 6,448,359;6,746,975; 6,969,553; 7,078,099; 7,344,668 and U.S. patent applicationpublication 2007/0231572, all of which are incorporated herein byreference. Particularly preferred fiber types are any of thepolyethylene fibers sold under the trademark SPECTRA® from HoneywellInternational Inc. including SPECTRA® 900 fibers, SPECTRA® 1000 fibersand SPECTRA® 3000 fibers, all of which are commercially available fromHoneywell International Inc. of Morristown, N.J.

The most preferred UHMW PE fibers have an intrinsic viscosity whenmeasured in decalin at 135° C. by ASTM D1601-99 of from about 7 dl/g toabout 40 dl/g, preferably from about 10 dl/g to about 40 dl/g, morepreferably from about 12 dl/g to about 40 dl/g, and most preferably,from about 14 dl/g to 35 dl/g. The most preferred UHMW PE fibers arehighly oriented and have a c-axis orientation function of at least about0.96, preferably at least about 0.97, more preferably at least about0.98 and most preferably at least about 0.99. The c-axis orientationfunction is a description of the degree of alignment of the molecularchain direction with the filament direction. A polyethylene filament inwhich the molecular chain direction is perfectly aligned with thefilament axis would have an orientation function of 1. C-axisorientation function (fe) is measured by the wide angle x-raydiffraction method described in Correale. S. T. & Murthy, Journal ofApplied Polymer Science, Vol. 101, 447-454 (2006) as applied topolyethylene.

When it is desired to utilize twisted elongate bodies, various methodsof twisting fibers/yarns are known in the art and any method may beutilized. In this regard, twisted multi-filament tapes are formed byfirst twisting a feed fiber/yarn precursor, followed by compressing thetwisted precursor into a tape. Useful twisting methods are described,for example, in U.S. Pat. No. 2,961,010; 3,434,275; 4,123,893; 4,819,458and 7,127,879, the disclosures of which are incorporated herein byreference. The fibers/yarns are twisted to have at least about 0.5 turnsof twist per inch of fiber/yam length up to about 15 twists per inch,more preferably from about 3 twists per inch to about 11 twists per inchof fiber/yarn length. In an alternate preferred embodiment, thefibers/yams are twisted to have at least 11 twists per inch of fiber/yamlength, more preferably from about 11 twists per inch to about 15 twistsper inch of fiber/yam length. The standard method for determining twistin twisted yarns is ASTM D1423-02. However, twisting is not preferred ifit is desired to achieve maximum stab resistance.

When it is desired to utilize fused elongate bodies, various methods offusing fibers/yarns are known in the art and any method may be utilized.Fused multi-filament tapes are formed by first fusing a feed fiber/yamprecursor followed by compressing the fused precursor into a tape. Inthis regard, fusion of the fiber/yam filaments may be accomplished bywith the use of heat and tension, or through application of a solvent orplasticizing material prior to exposure to heat and tension as describedin U.S. Pat. Nos. 5,540,990; 5,749,214; and 6,148,597, which are herebyincorporated by reference to the extent compatible herewith. Fusion bybonding may be accomplished, for example, by at least partially coatingthe filaments with a resin or other polymeric binder material havingadhesive properties, such as apolystyrene-polyisoprene-polystyrene-block copolymer resin commerciallyavailable from Kraton Polymers of Houston, Tex. under the trademarkKRATON® D1107, or any other adhesive polymer described herein. They mayalso be thermally bonded together without an adhesive coating. Thermalbonding conditions will depend on the fiber type. When the feedfibers/yarns are coated with a resin or other polymeric binder materialhaving adhesive properties to bond the filaments, only a small amount ofthe resin/binder is needed. In this regard, the quantity of resin/binderapplied is preferably no more than 5% by weight based on the totalweight of the filaments plus the resin/binder, such that the filamentscomprise at least 95% by weight of the coated fiber/yam based on thetotal weight of the filaments plus the resin/binder, and thecorresponding tape formed from the yarn will thereby also comprise atleast 95% by weight of the component filaments. More preferably, thefibers/yarns and tapes comprise at least about 96% filaments by weight,still more preferably 97% filaments by weight, still more preferably 98%filaments by weight, and still more preferably 99% filaments by weight.Most preferably, the fibers/yams and compressed tapes formed therefromare resin-free, i.e. are not coated with a bonding resin/binder, andconsist essentially of or consist only of filaments.

Methods of compressing fibers/yarns into tapes are described, forexample, in U.S. Pat. No. 8,236,119 and U.S. patent application Ser. No.13/568,097, each of which is incorporated herein by reference to theextent consistent herewith. Other methods for forming tapes, includingfrom twisted multifilament fibers/yarns and from untwisted multifilamentfibers/yarns, as well as non-fibrous tapes, are described in U.S. patentapplication Ser. Nos. 13/021,262; 13/494,641, 13/647,926 and 13/708,360,which are also incorporated herein by reference. These methods areuseful for forming tapes of this invention having any of the preferredaspect ratios described herein.

The woven fabric is formed using any commonly known weaving techniquewhere longitudinal warp elongate bodies are interwoven with transverselydisposed, lateral weft elongate bodies such that the elongate bodies arein an orthogonal 0°/90° orientation. Plain weave is most common. Otherweave types non-exclusively include crowfoot weave, basket weave, satinweave and twill weave.

A first embodiment is illustrated in FIG. 1 where a first set of hightenacity elongate bodies 10 are positioned as the longitudinallyextending warp bodies and a second set of high tenacity elongate bodies12 are transversely disposed as the lateral weft bodies. In a typicalprocess, the high tenacity warp elongate bodies 10 are unwound from aplurality of spools that are supported on one or more creels 14. Anarray of high tenacity elongate bodies 10 is led through a heddle 18which separates adjacent high tenacity elongate bodies 10 so that theyare spaced apart from each other (at their nearest longitudinal edges)by a distance equivalent to at least about 10% of the width of the hightenacity elongate bodies. This amount of separation ensures that thesubsequent thermal fusion step achieves a full and complete closure ofthe space between adjacent high tenacity elongate bodies 10 so thatabutting longitudinal edges of the elongate bodies 10 press against eachother such that they are substantially in contact with each otherwithout overlapping. In this regard, all of the high tenacity elongatebodies in the warp direction are preferably uniform in width and alsopreferably uniform in thickness. It is also preferred that all of thehigh tenacity elongate bodies in the weft direction are preferablyuniform in width and also preferably uniform in thickness. If notuniform in width, the separation distance should be calculated bymeasuring the elongate bodies at the location of greatest width. This isthe case for all warp and weft fibers of the invention. It is alsopreferred, although not required, that all the high tenacity bodies inthe warp direction have the same width and thickness as all the hightenacity bodies in the weft direction. Most preferably, all the warp andweft high tenacity elongate bodies are identical to each other. Thesubsequent thermal fusion step will accordingly fully close the spacebetween all adjacent high tenacity elongate bodies 10 and achieve afully closed, gapless woven fabric structure. Full, complete closure isnot mandatory but is most preferred.

In the more preferred embodiments of the invention, the heddle 18separates adjacent high tenacity warp elongate bodies 10 so that theyare spaced apart at their nearest longitudinal edges by at least about15% of the width of the high tenacity warp bodies, still more preferablyby about 15% to about 50% of the width of the high tenacity warp bodies,and most preferably from about 20% to about 30% of the width of the hightenacity warp bodies. In preferred embodiments of the invention, thesewidth percentages of separation measure to a separation of at leastabout 0.5 mm, more preferably 1 mm and still more preferably greaterthan 1 mm, still more by at least about 1.5 mm, still more preferably atleast about 2 mm, still more preferably by about 3 mm to about 30 mm andmost preferably by about 4 mm to about 20 mm. The separation must beless than about 50% of the width of the high tenacity warp bodies toensure that the thermal fusion step fully closes the space between alladjacent high tenacity warp elongate bodies 10 to achieve a fullyclosed, gapless woven fabric structure.

Referring again to FIG. 1, after the high tenacity warp elongate bodies10 pass through the heddle 18, the high tenacity weft elongate bodies 12are transversely interwoven with the high tenacity elongate bodies 10according to standard weaving techniques. The high tenacity weftelongate bodies 12 are unwound from one or more spools that aresupported on one or more creels 16. As illustrated in FIG. 7 whichillustrates a typical weaving process, conventional weaving positionsone long, continuous weft strand between each pair of adjacent warpstrands across the full width of the array of high tenacity elongatebodies 10. After passing the weft strand once across the array of warpstrands, the weaving machine turns the weft strand, reversing directionand passing back across the array of warp strands in the oppositedirection. As shown in FIG. 7, this forms selvage loops at the sideedges of the woven fabric which are typically trimmed or cut off duringfurther processing. When the selvage loops are trimmed or cut off, theresulting structure incorporates a plurality of discontinuous weftbodies in a substantially parallel array. When the selvage loops are nottrimmed or cut off, the resulting structure incorporates a single weftelongate body having a plurality of weft body portions where the weftbody portions are in a substantially parallel array. For each embodimentof this invention, such weft body portions of one long, continuous weftbody that are transversely disposed relative to the longitudinal warpbodies are to be interpreted as being a plurality of lateral weftbodies.

Equally useful in the practice of this invention is an alternativeweaving process used when tapes are inserted in the weft direction,whereby the continuous tape is pulled through the warp bodies in onlyone direction and the inserted tape is then cut at the fabric edge toform the new tape end that will next be pulled through the warp bodies,such that no selvage loops are formed.

The weaving equipment is set to space adjacent high tenacity weftelongate bodies 12 (such as adjacent parallel portions of one continuouselongate body 12) apart from each other by at least about 2 mm, morepreferably from about 3 mm to about 30 mm and most preferably from about4 mm to about 20 mm. As described herein, only the transversely disposedhigh tenacity weft elongate bodies are present in the space betweenadjacent high tenacity warp elongate bodies.

After the high tenacity weft elongate bodies 12 are woven through thehigh tenacity warp elongate bodies 10 in the weft direction, the hightenacity warp elongate bodies 10 and high tenacity weft elongate bodies12 are preferably thermally bonded together at their points ofintersection. Such thermal bonding is accomplished by at least partiallymelting the thermoplastic high tenacity elongate bodies with a heatingelement 22, thereby activating the thermoplastic polymers so that theyare capable of adhering to each other. The melted thermoplastic polymerof the high tenacity elongate bodies is then allowed to solidify. Oncethe polymer is solidified at the warp-weft body junction point, the hightenacity weft elongate bodies 12 are bonded to the high tenacity warpelongate bodies 10, thereby forming a dimensionally stable open fabric.

Heating element 22 is illustrated in FIG. 1 as a rectangular bar thatheats by direct contact with the high tenacity elongate bodies 12 (i.e.conductive heating). Heating may be accomplished by other suitablemethods, such as convective heating (e.g. hot air), radiant heating(e.g. infrared heating), as well as any other means of conductiveheating. However, relatively tight temperature control is required toonly partially melt the high tenacity bodies. Accordingly, conductiveheating methods are preferred. Most preferably, heating element 22 is aconductive heating element capable of applying pressure to the meltedhigh tenacity elongate bodies to assist in their bonding. Heatingelement 22 heats the high tenacity elongate bodies to a temperature offrom about 270° F. (˜132° C.) to about 330° F. (˜166° C.), morepreferably from about 280° F. (˜138° C.) to about 320° F. (˜160° C.),still more preferably from about 285° F. (˜141° C.) to about 315° F.(˜157° C.), and most preferably from about 290° F. (˜143° C.) to about310° F. (˜154° C.).

The bonding of the elongate bodies at the warp-weft crossing pointsmechanically stabilizes the open fabric structure by fixing the hightenacity weft elongate bodies 12 in their position and thereby achievingfixed gaps between the high tenacity elongate bodies 10 that aremaintained during fabric handling, preferably such that the dimensionsof all gaps in the fabric are identical. The heat from heating element22 is sufficient to make the high tenacity weft bodies 12 and/or thehigh tenacity warp bodies 10 tacky so that the bodies becomesufficiently bonded at the warp-weft crossing points.

This process produces a first dimensionally stable open woven fabricthat is preferably wound onto a first storage roll 24 and saved forlater processing. According to the process of the invention, a seconddimensionally stable open woven fabric is preferably fabricated andadjoined with the first open woven fabric. The second open woven fabricmay be identical to the first open woven fabric or different. Preferablythe second open woven fabric is fabricated according to the same methodsdescribed above for fabricating the first open woven fabric. The secondopen woven fabric is then preferably wound onto a second storage roll 26(illustrated in FIG. 3) and saved for later processing.

As shown in FIG. 1, optional tension rolls 20 may be provided to providetension to the warp fibers and assist in pulling the warp fibers towardfirst storage roll 24 (or to a second storage roll 26). Although theoptional tension rolls 20 are illustrated in FIG. 1 as being positionedbetween the heddle 18 and heating element 22, this position is onlyexemplary and may be placed in other locations or entirely eliminated aswould be determined by one skilled in the art. If the tension rolls 20are heated, they may assist in the thermal bonding process, and also mayreplace the function of the heating element 22 by applying adequate heatand pressure to cause partial melting and fusing at the warp-weftcrossover points.

The woven fabrics produced according to each of these two embodimentsare open fabrics having spaces or holes defined by the spacing ofadjacent warp bodies and the spacing of adjacent weft bodies. Inpreferred embodiments of the invention, only the transversely disposedweft elongate bodies are present between adjacent high tenacity warpelongate bodies. However, it is within the scope of the invention thatbinding elongate bodies may also be interwoven in the warp or weftdirections, said binding warp elongate bodies being positioned in thespace between adjacent high tenacity warp elongate bodies and/or in thespace between adjacent high tenacity weft elongate bodies. As usedherein, a “binding” elongate body is an elongate body that at leastpartially comprises a heat activated thermoplastic polymer having amelting temperature below a melting temperature of the high tenacityelongate bodies. Said binding elongate bodies may be single componentbinder element or multi-component elongate bodies. A single componentelongate body is a fiber, yarn or tape formed entirely from a heatactivated thermoplastic polymer having a melting temperature below amelting temperature of the high tenacity elongate bodies. Such areconventionally known in the art and non-exclusively include bodiescomprising ethylene-vinyl acetate, ethylene-acrylate copolymers, styreneblock copolymers, polyurethanes, polyamides, polyesters and polyolefins,including and most preferably polyethylene. Multi-component fibers, forexample bi-component fibers, are known having multiple distinctcross-sectional domains of distinct polymer types differing from eachother in composition (e.g., polyurethane and polyethylene) and/ordiffering in visual response, e.g., color. Bi-component fibers have twodistinct cross-sectional domains of two distinct polymer types. Varioustypes of bi-component fibers are known and include side-by-side fibers,sheath/core fibers (also known as sheathed core fibers) which may beconcentric or eccentric, pie wedge fibers, islands/sea fibers andothers. Such are well known in the art. Bi-component fibers and methodsfor their manufacture are described for example in U.S. Pat. Nos.4,552,603; 4,601,949; and 6,158,204, the disclosures of which areincorporated by reference herein to the extend compatible herewith.

When present, preferred are binding elongate bodies that comprisebi-component elongate bodies comprising a first component and a secondcomponent, wherein the first component comprises a heat activatedthermoplastic polymer having a melting temperature below a meltingtemperature of the high tenacity elongate bodies, and wherein the firstcomponent has a melting temperature that is below a melting temperatureof second component. Suitable heat activated thermoplastic polymers forthe first component non-exclusively includes those described above.Suitable second components comprising a bi-component fibernon-exclusively include the high tenacity polymer types described above.In a most preferred embodiment, the bi-component elongate bodies aresheathed core bi-component fibers, wherein the second polymer componentis a core fiber comprising a high tenacity monofilament fiber or a hightenacity multifilament fiber and the first polymer component is a sheathcomprising a heat activated, thermoplastic polymer. Preferred heatactivated thermoplastic polymers are described above. Preferred corefibers may be any thermoplastic or non-thermoplastic high tenacityfiber, including aramid fibers, carbon fibers, glass fibers. UHMW PEfibers and others. Most preferably, the core fiber is a glass fiber or aUHMW PE fiber. A most preferred single-component elongate body is a UHMWPE fiber, preferably a monofilament or monofilament-like UHMW PE fiber.A most preferred bi-component elongate body comprises a UHMW PE fibercore (preferably a monofilament or monofilament-like UHMW PE fiber)sheathed with an EVA thermoplastic polymer.

In preferred embodiments of the invention, when the binding bodies arepresent, they are preferably thermally bonded to the high tenacitybodies that are oriented perpendicular to the binding bodies at theirpoints of intersection by passage through heating element 22. Suchthermal bonding is accomplished by at least partially melting thethermoplastic polymer component of the binding elongate bodies with theheating element 22, thereby activating the thermoplastic polymer so thatit is capable of adhering to the high tenacity elongate bodies and thenallowing the melted thermoplastic polymer of the binding elongate bodies12 to solidify. This bonding step is preferably achieved withoutexternal pressure. The heat from heating element 22 is adequate enoughto make the adhesive coating of the binding bodies tacky so that thebodies become sufficiently bonded at the warp-weft crossing points, withinherent internal pressure of contact between crossing fibers in thewoven structure being sufficient to bond the bodies to each other. Oncethe polymer is solidified at the warp-weft body junction point with theperpendicular high tenacity elongate bodies, the binding elongate bodiesare bonded to the high tenacity elongate bodies, further enhancing thedimensional stability of the open fabric.

Whether the optional binding elongate bodies are single componentthermoplastic bodies or bi-component elongate bodies, the high tenacityelongate bodies preferably comprise at least about 90% by weight of thefabric, more preferably greater than about 90% by weight of the fabric,still more preferably at least about 95% by weight of the fabric, stillmore preferably at least about 98% by weight of the fabric, and mostpreferably at least about 99% by weight of the fabric. In this regard,when present, the binding elongate bodies are preferably incorporated ata pick per inch (ppi) of from about 5 picks per inch to about 15 picksper inch, preferably from about 5 picks per inch to about 10 picks perinch, or alternatively from about 10 picks per inch to about 15 picksper inch.

In accordance with the present invention, after the open fabricstructures are woven, they are then heated and pressed under conditionssufficient to flatten the thermoplastic, high tenacity elongate bodiesand thereby close the holes by causing edges of the adjacent hightenacity elongate bodies to contact each other. This thermal fusion maybe performed on a single open fabric to form a single closed, thermallyfused sheet as illustrated in FIG. 2 or may be performed on multipleadjoined open fabrics together to form a closed, thermally fusedmultilayer article in one step as illustrated in FIGS. 3 and 5.

As illustrated in FIG. 2, the thermal fusion process is preferablyconducted as a continuous process where a dimensionally stable openwoven fabric is unwound from a first storage roll 24 and passed throughpressure rolls 30. Rolls 30 are preferably heated to a temperature offrom about 200° F. (˜93° C.) to about 350° F. (˜177° C.), morepreferably from about 200° F. to about 315° F. (˜157° C.), still morepreferably from about 250° F. (˜121° C.) to about 315° F., and mostpreferably from about 280° F. (˜138° C.) to about 310° F. (˜154° C.).The most suitable temperature will vary depending on the melting pointof the polymer used to form the high tenacity elongate bodies. Rolls 30exert pressure on the open, woven fabric, pressing it at a pressure offrom about 50 psi (344.7 kPa) to about 50,000 psi (344.7 MPa), morepreferably about 500 psi (3.447 MPa) to about 20,000 psi (137.9 MPa) andmost preferably from about 1,000 psi (6.895 MPa) to about 10,000 psi(68.957 MPa). Pressing the open woven fabric through the heated pressurerolls 30 produces a thermally fused sheet having no gaps between thewarp elongate bodies without said bodies overlapping. If necessary, ineach embodiment of the invention, the fabric may be passed through rolls30 multiple times (or through additional rolls 30) to achieve thepreferred gapless, fully closed sheet structure. Driven roll 32 collectsthe fused sheet and provides a controlled tension in the sheet. Thesheet is preferably cooled to below the melting temperature of the hightenacity elongate bodies before contact with roll 32.

As illustrated in FIG. 3, the thermal fusion process is preferablyconducted as a continuous process where a first dimensionally stableopen woven fabric is unwound from a first storage roll 24 and a seconddimensionally stable open woven fabric is unwound from a second storageroll 26, with the two fabrics being adjoined and fused to each other bypassing through heated pressure rolls 30 according to the conditionsdescribed above. As illustrated in FIG. 4, a first dimensionally stableopen woven fabric is fused with a unidirectional array of longitudinalhigh tenacity elongate bodies supplied from a creel 14 rather than asecond dimensionally stable open woven fabric. Fusion is achieved bypassing through heated pressure rolls 30.

FIGS. 5 and 6 illustrate embodiments that include an additional set ofrolls (rolls 28) that are employed when one or more open woven fabricsinclude the optional binding elongate bodies (not shown). FIG. 5illustrates an embodiment where a first dimensionally stable, open wovenfabric is unwound from a storage roll 24 and attached to a second wovenfabric unwound from storage roll 26. The two fabrics are then attachedto each other by passage through a first set of rolls 28 before they arefused together between a second set of rolls 30. FIG. 6 illustrates anembodiment where a first dimensionally stable, open woven fabric isunwound from a storage roll 24 and a unidirectional array oflongitudinal high tenacity elongate bodies is supplied from a creel 14.The fabric and array of high tenacity bodies are then attached to eachother by passage through a first set of rolls 28 before they are fusedtogether between a second set of rolls 30. The binding elongate bodieshelp adhere the woven fabrics to each other (or the woven fabric to thearray of high tenacity bodies), and rolls 28 facilitate theirattachment. Rolls 28 are preferably heated to a temperature that isslightly above the melting point of the binding elongate bodies.Preferably rolls 28 are heated at a temperature that is no more than 10°C. above the melting temperature of the binding elongation bodies, andmost preferably at a temperature that is no more than 5° C. above themelting temperature of the binding elongation bodies. The most suitabletemperature will vary depending on the melting point of the polymer usedto form the binding elongate bodies. In the preferred embodiments, suchtemperatures for roll 28 are preferably from about 200° F. (˜93° C.) toabout 350° F. (˜177° C.), more preferably from about 200° F. to about315° F. (˜157° C.), still more preferably from about 250° F. (˜121° C.)to about 315° F., and most preferably from about 280° F. (˜138° C.) toabout 310° F. (˜154° C.). Rolls 28 also preferably exert light pressureon the fabrics (or fabric and web) to attach them to each other.

The adjoined/attached, heated fabrics are then continuously passedthrough pressure rolls 30, pressing them together as described above toform a fused sheet. When the binding elongate bodies are present, rolls30 are preferably heated to a temperature that is slightly below themelting point of the high tenacity elongate bodies. Preferably, rolls 30are heated at a temperature that is no more than 5° C. below the meltingtemperature of the high tenacity elongation bodies, and most preferablyat a temperature that is no more than 3° C. below the meltingtemperature of the high tenacity elongation bodies. Pressing theadjoined fabrics between heated pressure rolls 30 produces a thermallyfused sheet having no gaps between the warp elongate bodies without thebodies overlapping. Driven roll 32 collects the fused sheet and providesa controlled tension in the sheet. The sheet is preferably cooled tobelow the melting temperature of the high tenacity elongate bodiesbefore contact with roll 32. In each of the continuous roll processesdescribed herein, the duration of passage through rolls 30 and optionalrolls 28 will be at a rate of from about 1 meter/minute to about 100meters/minute, more preferably from about 2 meters/minute to about 50meters/minute, still more preferably from about 3 meters/minute to about50 meters/min. still more preferably from about 4 meters/minute to about30 meters/minute, and most preferably from about 5 meters/minute toabout 20 meters/minute.

In addition to the multi-stage continuous pressing process illustratedin FIGS. 5 and 6, it is possible to adjoin and flatten the two layers(i.e. two woven fabrics or a fabric and an array of high tenacitybodies) in a single continuous pressing stage. Multi-stage andsingle-stage batch processes using heated-platen presses can also beused to adjoin and flatten two or more layers of dimensionally stableopen woven fabrics of this invention, or one or more layers of fabricwith one or more arrays of high tenacity bodies.

In accordance with the invention, pressing the softened, spaced aparthigh tenacity elongate bodies 10 with sufficient pressure will flattenthem, reducing them in thickness while increasing them in width, wherebythe space between adjacent high tenacity elongate bodies issubstantially eliminated, and most preferably completely eliminated. Dueto such flattening and expansion of the width of the high tenacityelongate bodies, the nearest longitudinal edges of adjacent the hightenacity elongate bodies are brought into contact with each otherwhereby there are substantially no gaps between said adjacent hightenacity elongate bodies and wherein said adjacent high tenacityelongate bodies do not overlap, achieving a closed, thermally fusedsheet.

The high tenacity elongate bodies, including high tenacity fibers, yarnsand tapes, may be of any suitable denier. For example, fibers/yams mayhave a denier of from about 50 to about 10,000 denier, more preferablyfrom about 200 to 5,000 denier, still more preferably from about 650 toabout 4,000 denier, and most preferably from about 800 to about 3.000denier. Tapes may have deniers from about 50 to about 30.000, morepreferably from about 200 to 10,000 denier, still more preferably fromabout 650 to about 5,000 denier, and most preferably from about 800 toabout 3,000 denier. When present, the binding elongate bodies preferablyhave a denier of from about 20 to about 2000, more preferably from about50 to about 500, still more preferably from about 60 to about 400, andmost preferably from about 70 to about 300. The selection of elongatebody denier is governed by considerations of ballistic effectiveness andcost. Finer fibers/yarns/tapes are more costly to manufacture and toweave, but can produce greater ballistic effectiveness per unit weight.Multifilament tapes are typically formed by thermally fusing togetherfrom 2 to about 1000 filaments, more preferably from 30 to 500filaments, still more preferably from 100 to 500 filaments, still morepreferably from about 100 filaments to about 250 filaments and mostpreferably from about 120 to about 240 filaments. The greater number offilaments typically translates to higher tape deniers.

As the thermal pressing step will reduce the thickness of the elongatebodies, it will also reduce the thickness of the overall wovenstructure. The thickness of the open fabrics and closed, thermally fusedsheets will correspond to the thickness of the individual high tenacityelongate bodies before and after flattening, respectively. A preferredopen woven fabric will have a preferred thickness of from about 10 μm toabout 600 μm, more preferably from about 20 μm to about 385 μm and mostpreferably from about 30 μm to about 255 μm. A preferred closed,thermally fused sheet will have a preferred thickness of from about 5 μmto about 500 μm, more preferably from about 10 μm to about 250 μm andmost preferably from about 15 μm to about 150 μm.

A plurality of such single layer or multilayer closed, thermally fusedsheets may be fabricated according to the methods described herein, thenstacked on top of each other coextensively and consolidated to form aballistic resistant article having superior ballistic penetrationresistance. For the purposes of the invention, articles that havesuperior ballistic penetration resistance describe those which exhibitexcellent properties against deformable projectiles, such as bullets,and against penetration of fragments, such as shrapnel.

As used herein, “consolidating” refers to combining a plurality offabrics into a single unitary structure. For the purposes of thisinvention, consolidation can occur with heat and/or pressure or withoutheat and/or pressure and with or without an intermediate adhesivebetween fabrics/sheets. For example, the fused sheets may be gluedtogether, as is the case in a wet lamination process. Due to the uniqueprocess used to form the closed, thermally fused sheets, it is a uniquefeature of this invention that an intermediate adhesive coating isoptional and not required to form a ballistic resistant article. Theflat structure of the fused sheets allows them to be merely hot-pressedtogether with sufficient bonding according to conventional consolidationconditions. Consolidation may be done at temperatures ranging from about50° C. to about 175° C., preferably from about 105° C. to about 175° C.,and at pressures ranging from about 5 psig (0.034 MPa) to about 2500psig (17 MPa), for from about 0.01 seconds to about 24 hours, preferablyfrom about 0.02 seconds to about 2 hours. As is conventionally known inthe art, consolidation may be conducted in a calendar set, a flat-bedlaminator, a press or in an autoclave. Consolidation may also beconducted by vacuum molding the material in a mold that is placed undera vacuum. Vacuum molding technology is well known in the art.

To the extent that an intermediate adhesive is used, ballistic resistantarticles of the invention may be consolidated with a lower quantity ofadhesive resin than is typically needed for forming articles fromun-fused, uncompressed sheets because the adhesive need only be appliedas a surface layer without impregnating or coating the individualcomponent filaments of the component elongate bodies to promote bondingof one closed sheet to another closed sheet. Accordingly, the totalweight of an adhesive or binder coating in a composite preferablycomprises from about 0% to about 10%, still more preferably from about0% to about 5% by total weight of the component filaments plus theweight of the coating. Even more preferably, ballistic resistantarticles of the invention comprise from about 0% to about 2% by weightof an adhesive coating, or about 0% to about 1% by weight, or only about1% to about 2% by weight.

Suitable adhesive materials include both low modulus materials and highmodulus materials. Low modulus adhesive materials generally have atensile modulus of about 6,000 psi (41.4 MPa) or less according to ASTMD638 testing procedures and are typically employed for the fabricationof soft, flexible armor, such as ballistic resistant vests. High modulusadhesive materials generally have a higher initial tensile modulus than6.000 psi and are typically employed for the fabrication of rigid, hardarmor articles, such as helmets.

Representative examples of low modulus adhesive materials includepolybutadiene, polyisoprene, natural rubber, ethylene-propylenecopolymers, ethylene-propylene-diene terpolymers, polysulfide polymers,polyurethane elastomers, chlorosulfonated polyethylene, polychloroprene,plasticized polyvinylchloride, butadiene acrylonitrile elastomers,poly(isobutylene-co-isoprene), polyacrylates, polyesters, polyethers,fluoroelastomers, silicone elastomers, copolymers of ethylene,polyamides (useful with some filament types), acrylonitrile butadienestyrene, styrene-isoprene-styrene (SIS) block copolymers, elastomericpolyurethanes, polycarbonates, acrylic polymers, acrylic copolymers,acrylic polymers modified with non-acrylic monomers, and combinationsthereof, as well as other low modulus polymers and copolymers curablebelow the melting point of the non-polymeric tapes or of the filamentsforming the tapes. Also preferred are blends of different elastomericmaterials, or blends of elastomeric materials with one or morethermoplastics. Particularly preferred arepolystyrene-polyisoprene-polystyrene-block copolymers sold under thetrademark KRATON® from Kraton Polymers of Houston, Tex.

Preferred high modulus binder materials include polyurethanes (bothether and ester based), epoxies, polyacrylates, phenolic/polyvinylbutyral (PVB) polymers, vinyl ester polymers, styrene-butadiene blockcopolymers, as well as mixtures of polymers such as vinyl ester anddiallyl phthalate or phenol formaldehyde and polyvinyl butyral.Particularly suitable rigid polymeric binder materials are thosedescribed in U.S. Pat. No. 6,642,159, the disclosure of which isincorporated herein by reference to the extent consistent herewith. Apolymeric adhesive material may be applied according to conventionalmethods in the art.

When forming a multilayer article, a plurality of fabrics are overlappedatop each other, most preferably in coextensive fashion, andconsolidated into single-layer, monolithic element. In the mostpreferred embodiments, the high tenacity warp elongate bodies of a firstfabric are perpendicular to the high tenacity warp elongate bodies of asecond, adjacent fabric (i.e. 0°/90° high tenacity body orientationsrelative to the longitudinal axis of the warp bodies of each fabric,respectively), and this structure continues so that the high tenacitywarp elongate bodies in all odd numbered layers are oriented in the samedirection and the high tenacity weft elongate bodies in all evennumbered layers are oriented in the same direction. Although orthogonal0°/90° elongate body orientations are preferred, adjacent fabrics can bealigned at virtually any angle between about 0° and about 90° withrespect to the central longitudinal axis of warp bodies in anotherfabric. For example, a five fabric structure may have fabrics orientedat a 0°/45°/90°/45°/0° or at other angles, such as rotations of adjacentfabrics in 15° or 30° increments, with respect to the longitudinal axisof the high tenacity warp elongate bodies. Such rotated unidirectionalalignments are described, for example, in U.S. Pat. Nos. 4,457,985;4,748,064; 4,916,000; 4,403,012; 4,623,574; and 4,737,402, all of whichare incorporated herein by reference to the extent not incompatibleherewith.

Ballistic resistant, multilayer articles of the invention will typicallyinclude from about from about 2 to about 100 of the closed, thermallyfused sheets (layers), more preferably from about 2 to about 85 layers,and most preferably from about 2 to about 65 layers. The greater thenumber of plies translates into greater ballistic resistance, but alsogreater weight. The number of layers also affects the areal density ofthe composites, and the number of layers forming a desired compositewill vary depending upon the ultimate end use of the desired ballisticresistant article. Minimum levels of body armor ballistic resistance formilitary use are categorized by National Institute of Justice (NU)Threat Levels, as is well known in the art.

Multilayer articles of the invention comprising a consolidated pluralityof closed, thermally fused sheets of the invention preferably have anareal density of at least 100 g/m², preferably having an areal densityof at least 200 g/m² and more preferably having an areal density of atleast 976 g/m². Most preferably, such multilayer articles have an arealdensity of at least 4000 g/m² (4.0 ksm)(about 0.82 psf). In preferredembodiments, multilayer articles of the invention have an areal densityof from about 0.2 psf (0.976 ksm) to about 8.0 psf (39.04 ksm), morepreferably from about 0.3 psf (0.1.464 ksm) to about 6.0 psf (29.28ksm), still more preferably from about 0.5 psf (2.44 ksm) to about 5.0psf (24.4 ksm), still more preferably from about 0.5 psf (2.44 ksm) toabout 3.5 psf (17.08 ksm), still more preferably from about 1.0 psf(4.88 ksm) to about 3.0 psf (14.64 ksm), and still more preferably fromabout 1.5 psf (7.32 ksm) to about 3.0 psf (14.64 ksm). Articles of theinvention may be formed from a plurality of closed, thermally fusedsheets where each fused sheet comprises the same type of high tenacityelongate body, or where each fused sheet comprises a different type ofhigh tenacity elongate body. Alternately, a hybrid structure may beformed where the at least two different types of fused sheets areadjoined where the thermally fused sheets individually comprise multipledifferent high tenacity elongate body types in a single structure. Forexample, closed, thermally fused sheets may be fabricated from open,woven fabrics that include at least two different polymeric tape typeswherein a first tape type comprises polyethylene filaments and a secondtape type comprise polypropylene filaments. In another alternativeembodiment, woven fabrics may be fabricated from a combination offibrous tapes and non-fibrous tapes. In still another alternativeembodiment, one thermally fused sheet forming a multilayer article mayinclude binding fibers between the high tenacity elongate bodies whileanother thermally fused sheet of the article does not include anybinding fibers.

The multilayer composite articles of the invention may be used invarious applications to form a variety of different ballistic resistantarticles using well known techniques, including flexible, soft armorarticles as well as rigid, hard armor articles. For example, suitabletechniques for forming ballistic resistant articles are described in,for example, U.S. Pat. Nos. 4,623,574, 4,650,710, 4,748,064, 5,552,208,5,587,230, 6,642,159, 6,841,492 and 6,846,758, all of which areincorporated herein by reference to the extent not incompatibleherewith. The composites are particularly useful for the formation ofhard armor and shaped or unshaped sub-assembly intermediates formed inthe process of fabricating hard armor articles. By “hard” armor is meantan article, such as helmets, panels for military vehicles, or protectiveshields, which have sufficient mechanical strength so that it maintainsstructural rigidity when subjected to a significant amount of stress andis capable of being freestanding without collapsing. Such hard articlesare preferably, but not exclusively, formed using a high tensile modulusbinder material. The structures can be cut into a plurality of discretesheets and stacked for formation into an article or they can be formedinto a precursor which is subsequently used to form an article. Suchtechniques are well known in the art.

The following examples serve to illustrate the invention.

Example 1

Spools of high tenacity UHMWPE fibrous tape having a tenacity ofapproximately 33 g/denier were arranged in a creel. The tapes were madeaccording to a process described in U.S. Pat. No. 8,236,119. Theyaveraged about 3/16 inch wide and had an aspect ratio of greater than10:1. A plurality of the fibrous tapes were issued from the creel,arranged into a parallel array and fed to the header of a weavingmachine set for 5.3 tapes per inch in the warp direction with the tapesbeing spaced apart. The width of the parallel array of tapes to be wovenin the warp direction was about 16 inches wide. The same type of highstrength fibrous tape was used in the fill direction at about 5.3 tapesper inch to form a balanced basket weave. The result was a loosely wovenfabric having “holes” or “gaps” between the tapes in both the warp andfill directions.

Example 2

The woven fabric of Example 1 was cut into a sample measuring 16 inchesby 16 inches (L×W). This sample was then pressed for about 10 minutes at285° F. and 5000 psi together with a 6 mil thick film of low densitypolyethylene film on each outer surface. After pressing, the press wascooled down to 100° F. under pressure before the pressed fabric wasreleased. The resulting closed, fused sheet changed in appearance fromopaque to translucent and there were substantially no gaps or holes inthe pressed, fused sheet. A plurality of such fused sheets was formedaccording to the same process. The sheets were then positioned on top ofeach other coextensively to form a stack, and the stack was then pressedat 295° F. and 5000 psi on a 1500 ton press to form a consolidated panelhaving an areal density of 1 pound per square foot (psf).

Example 3

The fused sheets that were formed in Example 2 were stacked togetherwithout being pressed. The unconsolidated stack was then placed into asoft ballistic jacket to form a flexible body armor vest.

Example 4

A woven fabric formed in Example 2 was pressed as in example 2 butwithout the outer polyethylene films. The press temperature was 285° F.but the pressure was 2777 psig in a 200 ton press. The resulting fusedsheet showed substantially no gaps or holes between adjacent tapes.Several layers of these fused sheets were stacked together and pressedagain to consolidate the stack into an 8″×12″ (L×W) ballistic panel.

While the present invention has been particularly shown and describedwith reference to preferred embodiments, it will be readily appreciatedby those of ordinary skill in the art that various changes andmodifications may be made without departing from the spirit and scope ofthe invention. It is intended that the claims be interpreted to coverthe disclosed embodiment, those alternatives which have been discussedabove and all equivalents thereto.

1-11. (canceled)
 12. A process for forming a dimensionally stable openfabric, the process comprising: a) providing a woven fabric comprising aplurality of warp elongate bodies interwoven and bonded with a pluralityof transversely disposed weft elongate bodies, said warp elongate bodiesand weft elongate bodies each comprising thermoplastic high tenacityelongate bodies having a tenacity of at least about 14 g/denier and atensile modulus of at least about 300 g/denier, wherein adjacent warpelongate bodies are spaced apart from each other by a distanceequivalent to at least about 10% of the width of the warp elongatebodies and adjacent weft elongate bodies are spaced apart from eachother by a distance equivalent to at least about 10% of the width of theweft elongate bodies; b) at least partially melting the thermoplasticpolymer of the high tenacity warp elongate bodies and/or the hightenacity weft elongate bodies; and c) allowing the melted thermoplasticpolymer of the high tenacity warp elongate bodies and/or the hightenacity weft elongate bodies to solidify, whereby the high tenacitywarp elongate bodies and the high tenacity weft elongate bodies arebonded to each other, thereby forming a dimensionally stable openfabric.
 13. The process of claim 12 wherein adjacent warp elongatebodies are spaced apart from each other at their nearest longitudinaledges by more than 1 mm and adjacent high tenacity weft elongate bodiesare spaced apart from each other at their nearest longitudinal edges bymore than 1 mm.
 14. A process for forming a ballistic resistant closed,thermally fused multilayer article comprising adjoining at least twodimensionally stable open fabrics of claim 12 and thermally pressing theadjoined fabrics under conditions sufficient to attach the fabrics toeach other and to flatten the high tenacity warp and weft elongatebodies in each fabric respectively, thereby causing longitudinal edgesof adjacent warp high tenacity elongate bodies in each fabricrespectively to contact each other, whereby there are substantially nogaps between said adjacent high tenacity warp elongate bodies andwherein said high tenacity warp elongate bodies do not overlap; andthereby causing longitudinal edges of adjacent weft high tenacityelongate bodies in each fabric respectively to contact each other,whereby there are substantially no gaps between said adjacent hightenacity weft elongate bodies and wherein said high tenacity weftelongate bodies do not overlap.
 15. A process for forming a closed,fused sheet comprising pressing the dimensionally stable open fabric ofclaim 12 under conditions sufficient to flatten the high tenacity warpand weft elongate bodies in each fabric respectively, thereby causinglongitudinal edges of adjacent warp high tenacity elongate bodies ineach fabric respectively to contact each other, whereby there aresubstantially no gaps between said adjacent high tenacity warp elongatebodies and wherein said high tenacity warp elongate bodies do notoverlap; and thereby causing longitudinal edges of adjacent weft hightenacity elongate bodies in each fabric respectively to contact eachother, whereby there are substantially no gaps between said adjacenthigh tenacity weft elongate bodies and wherein said high tenacity weftelongate bodies do not overlap.
 16. A process for forming a ballisticresistant, closed multilayer article comprising attaching at least twoclosed, fused sheets of claim 15 to each other.
 17. A process forforming a ballistic resistant closed, thermally fused multilayer articlecomprising: a) providing at least one open woven fabric comprising aplurality of warp elongate bodies interwoven and bonded with a pluralityof transversely disposed weft elongate bodies, said warp elongate bodiesand weft elongate bodies each comprising thermoplastic high tenacityelongate bodies having a tenacity of at least about 14 g/denier and atensile modulus of at least about 300 g/denier, wherein adjacent warpelongate bodies are spaced apart from each other by a distanceequivalent to at least about 10% of the width of the warp elongatebodies and adjacent weft elongate bodies are spaced apart from eachother by a distance equivalent to at least about 10% of the width of theweft elongate bodies; b) providing at least one closed, fused sheetformed from a woven fabric, said woven fabric comprising a plurality ofwarp elongate bodies interwoven and bonded with a plurality oftransversely disposed weft elongate bodies, said warp elongate bodiesand weft elongate bodies each comprising thermoplastic high tenacityelongate bodies having a tenacity of at least about 14 g/denier and atensile modulus of at least about 300 g/denier; c) adjoining the atleast one open woven fabric and the at least one closed, fused sheettogether, and d) thermally pressing the adjoined open woven fabric andthe at least one closed, fused sheet together under conditionssufficient to attach the woven fabric to the fused sheet and to flattenthe high tenacity elongate bodies in the woven fabric, thereby causingthe longitudinal edges of the adjacent high tenacity warp elongatebodies in the woven fabric to contact each other, whereby there aresubstantially no gaps between said adjacent high tenacity warp elongatebodies and wherein said high tenacity warp elongate bodies do notoverlap.
 18. A process for forming a closed, thermally fused multilayerarticle comprising: a) providing an open woven fabric comprising aplurality of warp elongate bodies interwoven and bonded with a pluralityof transversely disposed weft elongate bodies, said warp elongate bodiesand weft elongate bodies each comprising thermoplastic high tenacityelongate bodies having a tenacity of at least about 14 g/denier and atensile modulus of at least about 300 g/denier, wherein adjacent warpelongate bodies ar spaced apart from each other by a distance equivalentto at least about 10% of the width of the warp elongate bodies andadjacent weft elongate bodies are spaced apart from each other by adistance equivalent to at least about 10% of the width of the weftelongate bodies; b) adjoining said open woven fabric with a webcomprising a parallel array of high tenacity elongate bodies, and c)thermally pressing the adjoined open woven fabric and web underconditions sufficient to attach the open woven fabric to the web and toflatten the high tenacity elongate bodies of both the open woven fabricand respectively, thereby causing longitudinal edges of the adjacenthigh tenacity elongate bodies in the open woven fabric and the webrespectively to contact each other, whereby there are substantially nogaps between said adjacent high tenacity elongate bodies and whereinsaid high tenacity elongate bodies do not overlap.
 19. A process forforming a closed, thermally fused multilayer article comprisingadjoining a closed, fused sheet formed in claim 18 with a web comprisinga parallel array of high tenacity elongate bodies and thermally pressingthe adjoined fused sheet and web under conditions sufficient to attachthe fused sheet to the web and to flatten the high tenacity elongatebodies of the web, thereby causing longitudinal edges of the adjacenthigh tenacity elongate bodies in the web to contact each other wherebythere are substantially no gaps between said adjacent high tenacityelongate bodies and wherein said high tenacity elongate bodies do notoverlap.
 20. The process of claim 12 further comprising weaving bindingwarp elongate bodies in the warp direction between said high tenacitywarp elongate bodies and/or weaving binding weft elongate bodies in theweft direction between said high tenacity weft elongate bodies, whereinsaid binding warp elongate bodies and said binding weft elongate bodieseach at least partially comprise a thermoplastic polymer having amelting temperature that is below a melting temperature of the hightenacity elongate bodies.